The present disclosure relates generally to electronic controllers that include an integrated temperature sensor. More specifically, the present disclosure relates to a controller in a heating, ventilating and air conditioning (HVAC) system that compensates for the heat generated by electronic components within the controller which affect the temperature measured by the integrated temperature sensor.
Electronic components within a zone controller (e.g., a wall-mounted thermostat) can generate heat during operation. The heat generated within the zone controller may cause the temperature within the zone controller to be higher than the actual ambient temperature of the building zone in which the controller is located. This temperature difference can adversely affect the performance of the building HVAC system if left uncorrected. For example, a feedback control system using the measured temperature as a feedback signal may heat or cool the building zone until the measured temperature reaches a temperature set point. Since the actual temperature of the building zone is cooler than the measured temperature, controlling the measured temperature to the set point can cause the actual temperature of the building zone to be cooler than the set point.
Previous techniques for compensating for the heat generated within a controller use the time that the controller (as a whole) has been powered on as the basis for internal heat generation. For example, U.S. Pat. No. 7,784,705 (“the '705 patent”) describes a temperature compensation method which calculates a corrected temperature as a function of the time since the controller was most recently powered up. The temperature compensation techniques described in the '705 patent assume that the controller generates heat at a constant rate when it is powered, regardless of how the controller is being used and independent of the control outputs provided by the controller.
The inventors of the present invention have recognized that the temperature compensation techniques described in the '705 patent fail to account for variable levels of internal heat generation within the controller and do not provide the granularity or adaptability to accurately model internal heat generation based on which components of the controller are currently active. It would be desirable to develop a temperature compensation technique that overcomes these and other disadvantages of the '705 patent.